Process of making stencil character punch and die sets



April 27, 1943. o. J. HERB 2,317,527

PROCESS OF MAKING STENCIL CHARACTER PUNCH AND DIE SETS Filed Nov. 27,1942 4 Q? 2 0021/7132: We

Patented Apr. 27, 1943 UNITED STATES PATENT OFFICE PROCESS OF MAKINGSTENCIL CHARACTER PUNCH AND DIE SETS Application November 27, 1942,Serial No. 467,131

10 Claims.

This invention, relates to the manufacture of mating character punch anddie sets for stencil cutting machines. The principal object of thepresent invention is to simplify and cheapen the process of making suchstencil character punch and die sets. The invention consists in theprocess hereinafter set forth and claimed.

In the accompanying drawing, which forms part of the specification andwherein like symbols refer to like parts Wherever they occur:

l is a vertical sectional view of a master punch and die set used-inpracticing my process,

Fig. 2 is a face view of a die plate made with the master punch and dieset shown in Fig. 1,

Fig. 3 is a similar view of a punch plate made with the same masterpunch and die set,

Fig. i is a cross-section through the punch plate on the line 4-4 inFig. 3, the recess formed in the top of said plate by the punched-outcharacter forming ribs on the bottom thereof being shown filled withsolder,

Fig. 5 is a similar cross-section through the die plate on the line 5-5in Fig. 2,

Fig. 6 is a vertical sectional view of a tank containing a corrosivefluid for enlarging the character forming openings of the die plate,

Fig. '7 is a. cross-sectional View through the die plate and a masterpunch plate after the character forming openings in said die plate havebeen enlarged to snugly receive the character ribs of said master punchplate,

Fig. 8 is a cross-sectional View of the punch plate, with the sides ofthe character forming ribs thereof, undercut adjacent to the bodythereof; and

Fig. 9 is a cross-sectional view, showing the punch and die plates afterthe punch plate ribs are forced into the distorted die plate openingsand the non-conforming sides of said ribs are sheared or shaved off bythe distorted edges of said openings.

In carrying out my present process, a master punch and die set includinga punch l and a die 2 is used to punch character forming ribs 3 in apunch plate 4, and corresponding character forming openings 5 in a dieplate 6. The character forming openings 5 extend clear through the dieplate 6; and the character forming ribs 3 are formed on the punch plate4 by pressing said ribs part-way therethrough, leaving integralconnections 1 between said ribs and punch plate and recesses B on theback of the latter, which recesses are preferably filled with solder 9so as to support and strengthen said ribs.

The die plate 6 is then subjected to the action of a chemical agent,such as nitric acid, which corrodes or cats away the'metal and thusuni-- fornily enlarges the character forming openings 5 in said plate tosnugly receive the ribs 3c of a master punch plate 4a which is made withthe master punch l and die 2 and is also provided with a solder filling9a in the recesses 3a bacl; o1 said'ribs. The die plate 5 is suspendedby an acid resisting wire it) in a suitable nitric acid solution llcontained in an acid resisting container l2; and, after the openings 5in said die piate are sufiiciently enlarged to snugly receive the ribs30 of the master punch plate 4a, saiddie plate is removed from saidsolution and rinsed in water to stop further corrosion and to protectthe hands of the operator. The die plate 6 is then hardened by suitableheat treatment, after which the punch plate opposing face of the said.hardened die plate is ground to provide sharp cutting edges along thecharacter forming openings 5 therein. As a result of the heat treatmentof the die plate 6, the character forming openings 5 therein aredistorted slightly so that the fit obtained between ribs 3a of themaster punch plate 4:: and the die plate openings 5 by the acid sizingof said openings is lost. However, the mating punch plate 4 for thehardened die plate 6 is left soft and a close fit of the characterforming ribs '3 of the relatively soft punch plate in the slightlydistorted character iormin openings 5 of the die plate is obtained byforcing said ribs into said openings, whereby the sharp edges oi theopenings of the hardened die shave oh the non-conforming sides of theribs of the relatively soft punch plate. As shown in the drawing, thesides of the character forming ribs 3 of the punch plate 4 are undercut,as at 13, adjacent to the body thereof, whereby the shavings l4 removedfrom the sides of said ribs by the punch plate are automaticallydetached therefrom when the cutting edges of the die plate openingsreach the undercut portions of said ribs.

The hereinbefore described process has several important advantages. Thecharacter forming holes 5 in the die plate 6 are quickly and easilyenlarged to fit the ribs 30. of the master punch plate 4a by the actionof the nitric acid solution or other suitable corrosive agent, therebyeliminating the slow, difiicult and expensive hand filing operationheretofore employed to enlarge said openings; and a close fit of thecharacter forming ribs of the punch plate of each punch and die plateset in the slightly distorted character forming openings of the hardeneddie plate of said set is readily obtained without hand filing or shapingmerely by forcing said ribs into said openings, the hardened die pla'teacting as a skinning or dressing die. By undercutting the sides of thepunch plate ribs, the shavings are detached therefrom without the use ofa separate hand tool.

If desired, the openings in the die plate 6 may be sized to fit the ribson the unhardened punch plate 4 with which said punch plate is to beused, thereby dispensing with the use of the master punch plate 40..However, the use of the master punch plate is preferable, because thesize and shape of the punch shape vary due to difference in texture andhardness of the metal and also because it makes it unnecessary to pairthe punch and die plates until the final sizing of the ribs of thehardened die plate.

What I claim is:

1. The process of making mating stencil character punches and dies whichconsist in punching character forming openings in a die plate andcorresponding character forming ribs on a punch plate with the samemaster punch and die, subjecting said die plate to the action of acorrosive agent to enlarge the character forming openings therein,hardening said die plate, and then forcing the character forming ribs ofsaid punch plate into the character forming openings in said hardeneddie plate to conform said ribs to said openings.

2. The process set forth in claim 1, wherein the sides of the punchplate ribs are undercut at the base prior to the conforming operation tofacilitate removal of shavings produced by said conforming operation.

3. The process of making mating stencil character punches and dies whichconsist in punching character forming openings in a die plate andcorresponding character forming ribs on a punch plate with the samemaster punch and die, subjecting said die plate to the action of acorrosive agent to enlarge the character forming openings therein,hardening said die plate by heat treatment, and then pressing said punchplate and die plate together to cause said die plate to shave the punchplate ribs to a close fit in the die plate openings.

'4. The process set forth in claim 3, wherein the sides of the punchplate ribs are undercut along the base prior to the shaving operation tofacilitate removal of the shavings produced thereby.

The process of making a stencil character punch and die set whichconsists in forming character forming openings in a die plate andcorresponding character forming ribs on a punch sponding to thecharacter forming ribs of said first mentioned punch plate, subjectingsaid die plate to the action of a corrosive agent to enlarge thecharacter forming openings therein to closely fit the ribs of saidmaster punch plate, hardening said die plate and then forcing thecharacter forming ribs of said first mentioned punch plate into thecharacter forming openings in said hardened die plate to conform saidribs to said openings.

'7. The process set forth in claim 6, wherein the sides of the ribs ofsaid first mentioned punch plate are undercut at the base prior to theconforming operation to facilitate removal of shavings produced by saidconforming operation.

8. The process of making mating stencil character punches and dies whichconsist in punching character forming openings in die plates andcorresponding character forming ribs on punch plates with the samemaster punch and die, adapting one of said punch plates for service as amaster punch plate, subjecting said die plates to the action of acorrosive agent to enlarge the character forming openings therein tosnugly receive the ribs of said master punch plate, hardening said dieplates, and then forcing the character forming ribs of a punch plateinto the character forming openings in a hardened die plate to conformthe ribs of said punch plate to the openings in said die plate.

9. The process set forth in claim 8, wherein the sides of the punchplate ribs are undercut at the base prior to the conforming operation tofacilitate removal of the shavings produced by said conformingoperation.

10. The process set forth in claim 8, wherein the master punch plate isproduced by the conforming operation, the sides of the punch plates areundercut prior to said conforming operation and the corrosive agentcomprising a nitric acid solution in which said die plates are immersed.

OTTO J. HERB.

